Serum thymosin α 1 levels in patients with chronic inflammatory autoimmune diseases

Thymosin alpha 1 (Tα1) is a powerful modulator of immunity and inflammation. Despite years of studies, there are a few reports evaluating serum Tα1 in health and disease. We studied a cohort of healthy individuals in comparison with patients affected by chronic inflammatory autoimmune diseases. Sera from 120 blood donors (healthy controls, HC), 120 patients with psoriatic arthritis (PsA), 40 with rheumatoid arthritis (RA) and 40 with systemic lupus erythematosus (SLE), attending the Transfusion Medicine or the Rheumatology Clinic at the Policlinico Tor Vergata, Rome, Italy, were tested for Tα1 content by means of a commercial enzyme-linked immunosorbent assay (ELISA) kit. Data were analysed in relation to demographic and clinical characteristics of patients and controls. A gender difference was found in the HC group, where females had lower serum Tα1 levels than males (P < 0·0001). Patients had lower serum Tα1 levels than HC (P < 0·0001), the lowest were observed in PsA group (P < 0·0001 versus all the other groups). Among all patients, those who at the time of blood collection were taking disease-modifying anti-rheumatic drugs (DMARD) plus steroids had significantly higher Tα1 levels than those taking DMARD alone (P = 0·044) or no treatment (P < 0·0001), but not of those taking steroids alone (P = 0·280). However, whichever type of treatment was taken by the patients, serum Tα1 was still significantly lower than in HC and there was no treatment-related difference in PsA group. Further prospective studies are necessary to confirm and deepen these observations. They might improve our understanding on the regulatory role of Tα1 in health and disease and increase our knowledge of the pathogenesis of chronic inflammatory autoimmune diseases.

Immunological Events during the Early Phase of Infection with Schistosoma Mansoni in Mice

Naturally occurring infection in humans or experimental infection in mice by Schistosoma mansoni lead to a Th1 towards Th2 switch of cytokine response in the chronic late phase of the disease. It has been proposed that an initial Th1 response is successively down-regulated and followed by an egg-antigen driven Th2 response. Here we report the results of a kinetic study on the capacity of spleen cells from experimentally infected Balb/c mice to produce Th1 or Th2 cytokines, following mitogen stimulation, during the phase which precedes the granulomatous response associated to egg-deposition. The main results were identified as an early increase in IL-4 and IL-10 Th2 cytokine production, particularly pronounced for IL-10, only a slight and delayed decrease in IL-2 production and an invariable or actually enhanced capacity to produce IFN-γ. The emergence of Th2 response was associated with only slight and delayed modifications in spleen lymphocyte subsets, mainly represented by a decrease in CD3+ T cells and an increase in B cells. The initial unbalance of the Th1/Th2 response precedes thus the egg-deposition and the chronic phase of the infection, being evident 3 weeks after the challenge with the parasite. This observation could represent a novel finding useful in understanding the complex mechanisms involved in the immunopathogenesis of schistosomiasis.

Thymic Hormones and Cytokines

The discovery and the first studies on thymic hormones (TH) are historically linked with their role on the developmental events of T lymphocytes that occur within the thymus. However, paradoxically, during the most recent years, much more information about the effects of TH on mature effector cells, in relation with those indicating their real functions during the T-cell differentation, have been, in fact, available.

Here we report an update discussion concerning the possible role of the cooperation between TH and cytokines in T-cell development. Moreover we illustrate the results obtained by us and other authors, demonstrating a strict connection between the action of thymosins, a family of peptides first isolated and purified from calf thymus (1), and that of cytokines.

Mechanism of Action of Thymosinα1: Does It Interact with Membrane by Recognition of Exposed Phosphatidylserine on Cell Surface? A Structural Approach

Thymosinα1 is a peptidic hormone with pleiotropic activity, which is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of micelles and vesicles assuming two tracts of helical conformation with a structural flexible break in between. The studies of the interaction of Thymosinα1 with micelles of mixed dipalmitoylphosphatidylcholine and sodium dodecylsulfate and vesicles with mixed dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylserine, the latter the negative component of the membranes, by (1)H and natural abundance (15)N NMR are herewith reported, reviewed, and discussed. The results indicate that the preferred interactions are those where the surface is negatively charged due to sodium dodecylsulfate or due to the presence of dipalmitoylphosphatidylserine exposed on the surface. In fact the unbalance of dipalmitoylphosphatidylserine on the cellular surface is an important phenomenon present in pathological conditions of cells. Moreover, the direct interaction of Thymosinα1 with K562 cells presenting an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was carried out.

A candidate anti-HIV reservoir compound, auranofin, exerts a selective 'anti-memory' effect by exploiting the baseline oxidative status of lymphocytes

Central memory (T_CM) and transitional memory (T_TM) CD4⁺ T cells are known to be the major cellular reservoirs for HIV, as these cells can harbor a transcriptionally silent form of viral DNA that is not targeted by either the immune system or current antiretroviral drug regimens. In the present study, we explored the molecular bases of the anti-HIV reservoir effects of auranofin (AF), a pro-oxidant gold-based drug and a candidate compound for a cure of AIDS. We here show that T_CM and T_TM lymphocytes have lower baseline antioxidant defenses as compared with their naive counterpart. These differences are mirrored by the effects exerted by AF on T-lymphocytes: AF was able to exert a pro-differentiating and pro-apoptotic effect, which was more pronounced in the memory subsets. AF induced an early activation of the p38 mitogen-activated protein kinase (p38 MAPK) followed by mitochondrial depolarization and a final burst in intracellular peroxides. The pro-differentiating effect was characterized by a downregulation of the CD27 marker expression. Interestingly, AF-induced apoptosis was inhibited by pyruvate, a well-known peroxide scavenger, but pyruvate did not inhibit the pro-differentiating effect of AF, indicating that the pro-apoptotic and pro-differentiating effects involve different pathways. In conclusion, our results demonstrate that AF selectively targets the T_CM/T_TM lymphocyte subsets, which encompass the HIV reservoir, by affecting redox-sensitive cell death pathways.

Bacterial Isolates from Severe Infections and Their Antibiotic Susceptibility Patterns in Italy: a Nationwide Study in the Hospital Setting

The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator-associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin-resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 microg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. Finally, Acinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.

Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity

Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase 1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation,sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates.

Low molecular weight, non-peptidic agonists of TrkA receptor with NGF-mimetic activity

Exploitation of the biologic activity of neurotrophins is desirable for medical purposes, but their protein nature intrinsically bears adverse pharmacokinetic properties. Here, we report synthesis and biologic characterization of a novel class of low molecular weight, non-peptidic compounds with NGF (nerve growth factor)-mimetic properties. MT2, a representative compound, bound to Trk (tropomyosin kinase receptor)A chain on NGF-sensitive cells, as well as in cell-free assays, at nanomolar concentrations and induced TrkA autophosphorylation and receptor-mediated internalization. MT2 binding involved at least two amino-acid residues within TrkA molecule. Like NGF, MT2 increased phosphorylation of extracellular signal-regulated kinase1/2 and Akt proteins and production of MKP-1 phosphatase (dual specificity phosphatase 1), modulated p38 mitogen-activated protein kinase activation, sustained survival of serum-starved PC12 or RDG cells, and promoted their differentiation. However, the intensity of such responses was heterogenous, as the ability of maintaining survival was equally possessed by NGF and MT2, whereas the induction of differentiation was expressed at definitely lower levels by the mimetic. Analysis of TrkA autophosphorylation patterns induced by MT2 revealed a strong tyrosine (Tyr)490 and a limited Tyr785 and Tyr674/675 activation, findings coherent with the observed functional divarication. Consistently, in an NGF-deprived rat hippocampal neuronal model of Alzheimer Disease, MT2 could correct the biochemical abnormalities and sustain cell survival. Thus, NGF mimetics may reveal interesting investigational tools in neurobiology, as well as promising drug candidates.

Herpesviruses and periodontal disease: a cautionary tale

Periodontitis is an inflammatory disease of bacterial origin, characterized by an inconstant progression of lesions affecting the tooth supporting tissues. In spite of more than half a century of research efforts, the clinician still lacks any specific molecular or microbial diagnostic tool to predict the progression of periodontal lesions. Recently, several reports have proposed a role for some herpesviruses in the etiology of destructive phases of periodontitis. This paper critically analyzes these data in the light of consolidated knowledge that was developed in the characterization of virus-bacteria cooperative interactions, and proposes new topics of investigation to clarify the role of herpesviral infections in periodontitis and their potential predictive role as markers of progression.

Antiviral and immunomodulatory properties of new pro-glutathione (GSH) molecules

Reduced glutathione (GSH) is present in millimolar concentrations in mammalian cells. It is involved in many cellular functions such as detoxification, amino acid transport, production of coenzymes, and the recycling of vitamins E and C. GSH acts as a redox buffer to preserve the reduced intracellular environment. Decreased glutathione levels have been found in numerous diseases such as cancer, viral infections, and immune dysfunctions. Many antioxidant molecules, such as GSH and N-acetylcysteine (NAC), have been demonstrated to inhibit in vitro and in vivo viral replication through different mechanisms of action. Accumulating evidence suggests that intracellular GSH levels in antigen-presenting cells such as macrophages, influence the Th1/Th2 cytokine response pattern, and more precisely, GSH depletion inhibits Th1-associated cytokine production and/or favours Th2 associated responses. It is known that GSH is not transported to most cells and tissues in a free form. Therefore, a number of different approaches have been developed in the last years to circumvent this problem. This review discusses the capacity of some new molecules with potent pro-GSH effects either to exert significant antiviral activity or to augment GSH intracellular content in macrophages to generate and maintain the appropriate Th1/Th2 balance. The observations reported herein show that pro-GSH molecules represent new therapeutic agents to treat antiviral infections and Th2-mediated diseases such as allergic disorders and AIDS.

Fluconazole resistance in Candida albicans: a review of mechanisms

Antifungal agents have greatly contributed to the improvement of public health. Nevertheless, antifungal resistant pathogens have increased during the past decade, becoming a serious concern. Candida albicans has been the most extensively studied pathogen in antifungal resistance because of their morbidity and mortality associated with infections in immunocompromised patients. This review describes the antifungal mechanims of the azole fluconazole widely used for the prophylaxis and treatment of candidal infections. The specific molecular pathways occurring in fluconazole-resistance of C. albicans and some issues about new antifungal agents are also discussed.

Combination therapy in the treatment of chronic viral hepatitis and prevention of hepatocellular carcinoma

Treatment of chronic hepatitis B and C viruses (HBV and HCV) is still disappointing, and both are the major causes of liver cirrhosis and hepatocarcinoma. Interferon and lamivudine are the registered drugs for chronic HBV but are scarcely effective on HBeAg-negative patients, and resistance due to virus mutation is the rule with lamivudine. Interferon and ribavirine represent the standard treatment for chronic HCV but less than the half of the infected population is eligible for this treatment and less of the half of treated patients will experience a sustained response. No single new drug to date has shown the potential to overcome this dismal picture. Combined strategies are thus the currently most available approach to improve the response rate of chronic HBV and HCV infection, with a subsequent decrease in the number of patients developing hepatocellular carcinoma (HCC). Combination of thymosin alpha 1 with interferon or antiviral agents is currently the most promising option, but nontoxic immunomodulants, such as oral MIMP, should be explored. This review focuses on the difficulties with current therapy and the rationale for use of combination therapy with thymosin alpha 1 for both HBV and HCV therapies.

Synthesis, biological evaluation, and pharmacophore generation of uracil, 4(3H)-pyrimidinone, and uridine derivatives as potent and selective inhibitors of parainfluenza 1 (Sendai) virus

Several new 6-oxiranyl-, 6-oxiranylmethyluracils, and pyrimidinone derivatives, synthesized by lithiation-alkylation sequence of 1,3,6-trimethyluracil, 1,3-dimethyl-6-chloromethyluracil, and 2-alkoxy-6-methyl-4(3H)-pyrimidinones, showed a potent and selective antiviral activity against Sendai virus (SV) replication. To gain insight into the structural features required for SV inhibition activity, the new compounds were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of these inhibitors of SV replication.

Nerve growth factor inhibits apoptosis in memory B lymphocytes via inactivation of p38 MAPK, prevention of Bcl-2 phosphorylation, and cytochrome c release

Survival of memory B lymphocytes is tightly linked to the integrity of the Bcl-2 protein and is regulated by a nerve growth factor (NGF) autocrine circuit. In factor-starved memory B cells, the addition of exogenous NGF promptly induced p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase (JNK), dephosphorylation. Conversely, withdrawal of endogenous NGF was followed by p38 MAPK activation and translocation onto mitochondria, whereby it combined with and phosphorylated Bcl-2, as assessed by co-immunoprecipitation and kinase assays in vivo and in vitro. Mitochondria isolated from human memory B cells, then exposed to recombinant p38 MAPK, released cytochrome c, as did mitochondria from Bcl-2-negative MDCK cells loaded with recombinant Bcl-2. Apoptosis induced by NGF neutralization could be blocked by the specific p38 MAPK inhibitor SB203580 or by Bcl-2 mutations in Ser-87 or Thr-56. These data demonstrate that the molecular mechanisms underlying the survival factor function of NGF critically rely upon the continuous inactivation of p38 MAPK, a Bcl-2-modifying enzyme.

Macrophages: a crucial reservoir for human immunodeficiency virus in the body

The replication of Human Immunodeficiency Virus (HIV) in cells of macrophage lineage represents a key pathogenetic event of the neurological damages typically found during the course of this disease. Macrophages are persistently infected cells and thus not susceptible to the cytophatic effect typical of infected activated CD4-lymphocytes. The resistance of macrophages to HIV infection is at least in part mediated by the autocrine production of the nerve growth factor (NGF), a neurokine able to sustain the survival of some cells of bone marrow origin, including monocyte-derived macrophages. This anti-apoptotic effect of NGF in HIV-infected macrophages can be even more relevant at the central nervous system level, where many cells are able to physiologically produce NGF, thus further increasing the survival of macrophages infected by HIV, and enhancing the damages that these cells may induce upon bystander neurons. The proapoptotic effect of soluble factors released by HIV-infected macrophages may heavily affect the survival and functions also of astrocytes, that in turn become unable to sustain neuronal homeostasis. Taken together, this information supports the importance of therapeutic attempts aimed at attacking virus replication in infected macrophages and/or to selectively eliminate these chronically infected and persistently virus-producing cells.

Thymosin alpha 1 in the treatment of cancer: from basic research to clinical application

Many studies have explored the effects of immunotherapy, alone or in combination with conventional therapies, on both experimental and human cancers. Evidence has been provided that combined treatments with thymosin alpha 1 (T alpha 1) and low doses of interferon (IFN) or interleukin (IL)-2 are highly effective in restoring several immune responses depressed by tumor growth and/or cytostatic drugs. In addition, when combined with specific chemotherapy, they are able to increase the anti-tumor effect of chemotherapy while markedly reducing the general toxicity of the treatment. The advantages of using this combined chemo-immunotherapeutic approach in experimental and human cancers are reviewed in this issue.

NGF withdrawal induces apoptosis in CESS B cell line through p38 MAPK activation and Bcl-2 phosphorylation

The sIgG(+) lymphoblastoid B cell line CESS spontaneously produces a high amount of NGF and expresses both high affinity (p140(Trk-A)) and low affinity (p75(NTR)) NGF receptors. Blocking NGF signals with neutralizing antibodies or specific Trk-A inhibitors induces a rapid phosphorylation of antiapoptotic Bcl-2 protein, followed by caspase activation, and apoptotic death of CESS cells. Bcl-2 phosphorylation in several sites within a approximately 60 aa "loop" domain of protein is known to regulate its antiapoptotic function. Accordingly, CESS cells expressing the loop deletional mutant cDNA constructs Bcl-2 Delta40-91 were completely resistant to apoptosis induced by NGF withdrawal, indicating that Bcl-2 phosphorylation is a critical event. NGF withdrawal induces p38 MAPK, but not JNK, activation in CESS cells, and SB203580, a specific inhibitor of p38 MAPK, is able to prevent both Bcl-2 phosphorylation and apoptosis, indicating that p38 MAPK is the enzyme responsible for these events.

Autocrine nerve growth factor is essential for cell survival and viral maturation in HHV-8-infected primary effusion lymphoma cells

High levels of nerve growth factor (NGF) are found in sera from individuals infected with human herpesvirus 8 (HHV-8). BC-1 and BCBL-1 cells are primary effusion lymphoma-derived B-cell lines; BC-1 cells are infected by HHV-8 and the Epstein-Barr virus (EBV), and BCBL-1 cells are infected only by HHV-8. Both cells express NGF receptors and produce NGF, whereas RAMOS cells (a B-cell line that is negative for HHV-8 and EBV) express NGF receptors but do not produce detectable NGF. Neutralization of endogenous NGF results in cell growth inhibition and apoptosis in BCBL-1 cells and, to a minor extent, in BC-1 cells. When the HHV-8 lytic cycle is induced in BCBL-1 cells by tetradecanoyl phorbol acetate (TPA), an initial reduction of endogenous NGF production is observed, and many cells undergo apoptosis. However, at 48 hours, TPA-treated cells produce significantly more NGF than untreated controls, and a subsequent recovery of cell viability is observed. Consistent with this finding, the addition of exogenous NGF or anti-NGF antibodies to TPA-treated cells reduces or increases, respectively, the rate of apoptosis in response to TPA. Finally, electron microscopy of TPA-treated BCBL-1 cells shows that the addition of exogenous NGF increases the number of cells producing and releasing complete virions as compared with the controls (25% versus 5%). On the contrary, NGF neutralization leads to the production of defective viral progeny in about 2% of cells. These data indicate that NGF is essential for both cell survival and virus maturation in HHV-8-infected cell lines. (Blood. 2000;95:2905-2912)

Thymosin-alpha1 regulates MHC class I expression in FRTL-5 cells at transcriptional level

In this study we examined the effect of the synthetic peptide thymosin-alpha1 (T(alpha)1) on MHC class I expression in FRTL-5 cells. Treatment with T(alpha)1 increased expression of MHC class I surface molecules and mRNA, which reached its peak (153 +/- 8 % of the control value) after 12 h. Chloramphenicol acetyltransferase (CAT) analysis, following transfection with a plasmid containing the regulatory sequence of MHC class I (or its deletion derivatives) with the CAT reporter gene, and electrophoretic mobility shift assay experiments demonstrated that the action of T(alpha)1 was at the transcriptional level, and its mechanism of action is likely due to increased binding between the complex p50/fra-2 and the enhancer A sequence of the 5' flanking region of a swine class I gene (PD1). An increase in the expression of MHC class I surface molecules was also observed by flow cytometry in murine and human tumor cell lines and in primary cultures of human macrophages. This study shows for the first time an effect of Talpha1 on the regulation of gene expression at the molecular level, and may further contribute to explaining the results obtained using Talpha1 in the control of infectious diseases and tumor growth.

Imbalance in corneal redox state during herpes simplex virus 1-induced keratitis in rabbits. Effectiveness of exogenous glutathione supply

A significant decrease in the antioxidant glutathione (GSH) was found in the corneal tissue of rabbits with Herpes Simplex 1 (HSV-1)-induced keratitis. Such a decrease was due to a loss of the reduced species, since no increase in its oxidized form was observed. Topical administration of purified GSH was able to reduce the virus titre in corneal tissue and, at the same time, was effective in reducing the severity and progression of keratitis and conjunctivitis. This effect was paralleled by a partial recovery in the corneal GSH content. In vitro experiments performed on HSV-1 infected corneal-derived rabbit cells showed that exogenous GSH reduced virus titre in the supernatant of infected cells. These results are in agreement with our previous findings that an oxidative environment, due to GSH depletion, is necessary for virus replication and suggest that topical GSH treatment could be considered as complementary therapy in HSV-1-induced keratitis.

Effects of cocaine administration to influenza virus-immunized mice on cytokine profiles of individual splenic CD4+ and CD8+ T cells

We have analysed the effects of cocaine, administered to mice during the in vivo differentiation of effector T cells stimulated by antigen (influenza virus) recognition, on the frequency of IL-2-, IL-4- and interferon-gamma (IFN-gamma)-expressing CD4+ and CD8+ T cells. Each animal was injected intraperitoneally with 10 mg/kg of cocaine 6, 24, 48 and 72 h after immunization with A/PR8 influenza virus (PR8). This enabled the determination of the pharmacological effects of cocaine on T cells during the initial step of the immune response, which is characterized by the production of large amounts of immunoregulatory cytokines. The distribution of IL-2-, IL-4- and IFN-gamma-producing CD4+ and CD8+ T cells was assayed on unseparated PR8-immune spleen cells, obtained from mice treated with cocaine or vehicle, and restimulated in vitro with UV-inactivated PR8 virus. The frequency of T cells singly or co-expressing the above three cytokines was determined at single-cell level by simultaneous flow cytometric analysis of intracellular cytokines and surface antigen expression. In parallel, the levels of IL-2, IL-4 and IFN-gamma in the culture supernatants were quantified by ELISA. The results showed that cocaine, administered during the in vivo virus-induced differentiation of T cells, caused an increase of both the frequencies of CD8+ T cells singly and co-expressing IL-2 and IFN-gamma and the levels of these cytokines in virus-restimulated spleen cell culture supernatants, compared with those of untreated controls. In contrast, no effect was found on IL-4-positive CD8+ T cells and on IL-2-, IFN-gamma- and IL-4-positive CD4+ T cells. Our findings suggest that the immunomodulatory effects of cocaine may be due to the up-regulation of the production of IL-2 and IFN-gamma by CD8+ T cells with a type 0 cytokine profile.

Nerve growth factor is an autocrine factor essential for the survival of macrophages infected with HIV

Nerve growth factor (NGF) is a neurotrophin with the ability to exert specific effects on cells of the immune system. Human monocytes/macrophages (M/M) infected in vitro with HIV type 1 (HIV-1) are able to produce substantial levels of NGF that are associated with enhanced expression of the high-affinity NGF receptor (p140 trkA) on the M/M surface. Treatment of HIV-infected human M/M with anti-NGF Ab blocking the biological activity of NGF leads to a marked decrease of the expression of p140 trkA high-affinity receptor, a concomitant increased expression of p75(NTR) low-affinity receptor for NGF, and the occurrence of apoptotic death of M/M. Taken together, these findings suggest a role for NGF as an autocrine survival factor that rescues human M/M from the cytopathic effect caused by HIV infection.

Cocaine potentiates the switch between latency and replication of Epstein-Barr virus in Raji cells

This paper shows that cocaine amplifies Epstein-Barr virus (EBV) reactivation in Raji cells. Its effect on early viral protein synthesis was maximal when it was added with 12-O-tetradecanoyl phorbol-13-acetate (TPA) plus n-butyrate, but nil when added alone. The enhancing effect of cocaine on early replicative stages of latent EBV was associated with an increase of Ca(2+) mobilization induced by the drug and with an induction of cellular protein phosphorylation in chemicals and cocaine-treated Raji cells. Cocaine also acted synergistically with TPA and n-butyrate to induce Z Epstein-Barr replication activator (ZEBRA), a nuclear phosphoprotein responsible for the activation of early viral gene expression. These findings provide the first evidence that cocaine may represent an important co-factor in the reactivation of early stages of latent EBV infection.

Interferon-alpha-induced inhibition of B16 melanoma cell proliferation: interference with the bFGF autocrine growth circuit

The molecular mechanisms underlying the growth inhibition induced by interferon-alpha (IFN-alpha) in B16 murine melanoma cells were investigated. IFN-alpha did not induce cell apoptosis, but strongly interfered with the synthesis of basic fibroblast growth factor (bFGF), which acts as an autocrine growth factor in this system. Inhibition of bFGF synthesis was observed at the same concentrations (50-500 pM, 10-100 U/ml) of IFN-alpha able to induce growth arrest of B16 melanoma cells. Although the synthesis of acidic (a)FGF was only slightly affected by IFN-alpha, the cytokine induced release of an aFGF-related low-molecular-weight peptide, which was able to interfere with bFGF binding to surface receptors. Thus, the molecular mechanisms of IFN-alpha activity on melanoma cells include a specific modulation of the bFGF autocrine circuit.

Differential expression of a new tumor-associated antigen, TLP, during human colorectal cancer tumorigenesis

Tumour liberated particles (TLP) have been proposed as a potential new serum tumor marker. In particular, a high percentage of patients with early stages of lung cancer scored positive for serum TLP, suggesting its possible role as a marker for early diagnosis of disease. The aim of the present study was to analyze the expression of TLP in the colorectal adenoma-carcinoma sequence in order to determine whether its expression correlates with the various stages of cancer transformation. TLP distribution was assessed by immunohistochemistry in normal, premalignant, and malignant colorectal lesions. Normal colonic mucosa and hyperplastic polyps showed no positive staining, whereas adenomas and adenocarcinomas reacted to anti-TLP serum. The percentage of positive tumor cells increased from adenomas with mild dysplasia to adenomas with severe dysplasia. Moreover, a supranuclear staining pattern was observed mainly in adenomas with mild dysplasia, whereas adenomas with severe dysplasia as well as adenocarcinomas showed a characteristic diffuse staining pattern and a strong staining intensity. Only a few cases of adenocarcinoma were found to be TLP-negative and all were poorly differentiated. Our results suggest that TLP antigen expression may be considered as a marker of epithelial atypia in the colorectal tract and as a potential target for new diagnostic and/or therapeutic approaches to human colorectal cancer.

Differential effects of acute morphine administrations on polymorphonuclear cell metabolism in various mouse strains

This paper shows that an acute morphine treatment dose-dependently alters the energetic and oxidative metabolism of polymorphonuclear leukocytes obtained from BALB/c and DBA/2 mice, while phagocytic cells from C57BL/6 were not affected. In sensitive mouse strains, i.e. BALB/c and DBA/2, morphine decreased both ATP concentration and energy charge potential. At the same time, ATP catabolic products, i.e. nucleosides (inosine+adenosine) and oxypurines (hypoxanthine+xanthine+uric acid), significantly increased, indicating an imbalance between energy production and consumption. Morphine treatment also induced malondialdehyde and superoxide anions production in leukocyte cells from sensitive mice. The opiate antagonist naloxone blocked morphine-induced modifications by the lower morphine dose. The same parameters in cells from C57BL/6 mice were not affected. These findings confirm that: i) the phagocytic cells are an important target for the in vivo effects of morphine, and ii) the genotype-dependent variation influences the immunological responsiveness to opiates.

Cocaine induced T cell proliferation in the rat: role of amygdala dopamine D1 receptors

The immunomodulatory effects of local administration of cocaine into the amygdala were studied in the rat. Intra-amygdala infusion of cocaine significantly and dose-dependently increased the proliferative response of splenocytes to concanavalin A (Con A). A similar effect on the immune response was also observed in rats, microinfused into the central amygdala with the selective D1 receptor agonist SKF 38393. The increase of the proliferative response of splenocytes to Con A was inhibited by coinfusion within the central amygdala of the dopamine D1 receptor antagonist SCH 23390, together with cocaine, but not by coinfusion of the dopamine D2 receptor antagonist eticlopride. These results suggest that cocaine may produce at least some of its effects on the immune system through the activation of brain dopamine neurotransmission and that the central amygdala may represent a critical structure mediating cocaine-induced T cell proliferation.

Determination of cytokine co-expression in individual splenic CD4+ and CD8+ T cells from influenza virus-immune mice

We have studied the patterns of interleukin-2 (IL-2), IL-4 and interferon-gamma (IFN-gamma) co-expression displayed by individual splenic CD4+ and CD8+ T cells in response to influenza virus immunization. Unseparated spleen cells obtained from mice intraperitoneally (i.p.) injected with A/PR8 (H1N1) influenza virus (PR8) were cultured for 24 hr in the presence of ultraviolet-inactivated PR8. As controls, cultures of both naive spleen cells stimulated with PR8 or of immune cells lacking the inactivated virus were used. The frequencies of CD4+ and CD8+ T cells expressing IL-2, IL-4 and IFN-gamma were determined by three-colour flow cytometric analysis of fixed and saponin-permeabilized cells fluorescent-stained for either CD4 or CD8 surface molecules and for one of the following combinations of two intracellular cytokines: IL-2/IL-4, IL-2/IFN-gamma and IL-4/IFN-gamma. The results showed that immunization with influenza virus induces in both CD4+ and CD8+ T cells a heterogeneity of cytokine response patterns that do not follow the type 1/type 2 polarized response model, but with substantial differences between the two populations. In fact, the analysis of the phenotypes of virus-immune CD8+ T cells revealed similar significant proportions of cells either expressing any one of the three cytokines or co-expressing combinations of them (i.e. IL-4/IL-2, IL-4/IFN-gamma and IL-2/IFN-gamma), whereas immune CD4+ T cells were seen to express almost exclusively a single cytokine per cell. The observed patterns of cytokine production suggest that influenza virus immunization induces the expression of a type 0 cytokine pattern at both population and single cell levels in CD8+ T cells and exclusively at the population level in CD4+ T cells.

Detection of high nerve growth factor serum levels in AIDS-related and -unrelated Kaposi's sarcoma patients

OBJECTIVE

Nerve growth factor (NGF) is an autocrine survival factor for memory B lymphocytes. As functional B-cell deregulation is present during HIV infection, NGF serum levels were measured in HIV-infected patients and compared with the patients' clinical features.

DESIGN

Sera from 48 consecutive HIV-infected patients and matched healthy controls were retrospectively and blindly analysed. Sera from seven patients with classical Kaposi's sarcoma (KS) were subsequently included in the study. The effects of NGF on spindle-shaped cells from KS lesions (KS cells) were also investigated.

METHODS

NGF titration was performed by enzyme-linked immunosorbent assay (ELISA) and human herpesvirus 8 (HHV-8) antibody testing by immunofluorescent assay (IFA). NGF receptors were assessed by Western blot analysis. Cell growth assays were performed by cell counting.

RESULTS

Very high median NGF serum levels were detected in all seven patients with AIDS-related KS (2500 pg/ml) compared with HIV-infected patients without KS (40 pg/ml), as well as in all seven classical KS patients (550 pg/ml) compared with healthy controls (20 pg/ml). In HIV-infected patients, NGF serum levels were significantly related to KS (P=0.0038) by stepwise multiple regression analysis, and HHV-8 seropositivity was significantly associated with KS (P=0.045) and to NGF levels (P=0.001) by logistic regression analysis. KS cells did not produce NGF but expressed both NGF receptors and presented increased proliferation rate after exogenous NGF addition.

CONCLUSIONS

These results strongly suggest that increased NGF levels, possibly related to HHV-8 infection, may be involved in KS progression.

Cytoplasmic localization of anthracycline antitumor drugs conjugated with reduced glutathione: a possible correlation with multidrug resistance mechanisms

The accumulation of adriamycin (ADR), daunomycin (DAUNO) and their glutathione (GSH)-conjugates, recently obtained by anaerobic reaction of the parent anthracyclines with reduced GSH, was examined in drug-sensitive and multidrug resistant (MDR) cell lines using confocal laser scanning microscopy. In all drug-sensitive lines used (TVM-A12 and TVM-A197 human melanoma cells, K562 lymphoblastoid cells and MCF-7 human breast cancer cells) ADR and DAUNO were mostly located in the nuclei, while their GSH-conjugates were found only in the cytoplasm, predominantly in the Golgi region. On the contrary, in MDR MCF-7/Dox cells, both conjugated and non conjugated anthracyclines gave fluorescence only in the cytoplasm, mostly in the Golgi region, the intensity of the fluorescence being stronger in cells pretreated with verapamil. Viability assay showed that the GSH-conjugate are significantly less cytotoxic than the parent anthracyclines in sensitive cells and showed the same scarce cytotoxicity in MDR MCF-7/Dox cells. These results demonstrate that conjugation of anthracycline antitumor drugs with GSH prevents their access to the nucleus and decreases their cytotoxicity. Furthermore, the observations on MCF-7/Dox suggest that GSH-conjugation of anthracycline might occur in resistant cells and can be in part responsible for the MDR in breast cancer cells.

The conformation of peptide thymosin alpha 1 in solution and in a membrane-like environment by circular dichroism and NMR spectroscopy. A possible model for its interaction with the lymphocyte membrane

The 28-residue peptide thymosin alpha1 was studied by circular dichroism and two-dimensional NMR. Circular dichroism indicates that thymosin alpha1 in water solution does not assume a preferred conformation, while in the presence of small unilamellar vesicles of dimiristoylphosphatidylcholine and dimiristoylphosphatidic acid (10:1) and in sodium dodecyl sulphate, it assumes a partly structured conformation. Presence of zinc ions produces similar effects. In a more hydrophobic environment like a solution of a mixed solvent water-2,2,2 trifluoroethanol, it adopts a structured conformation. NMR spectra indicated that in this mixture as solvent, thymosin alpha1 has a structure characterized by two regions. A beta-turn is present between residue 5 and residue 8, while the region between residues 17 and 24 shows an alpha helix conformation. These changes of conformation in different environments may be considered structural requirements in the steps of its interaction with the lymphocyte membrane. In fact, these conformational changes may correspond to the first event of the mechanism of lymphocyte activation in the immune response modulation by thymosin alpha1.

Interleukin 4 stimulates infection and temporary growth of human neonatal lymphocytes exposed in vitro to human T-lymphotropic virus type I, but fails to substitute for interleukin 2 in the immortalization of infected cultures

It has been shown that interleukin 4 (IL-4) stimulates the proliferation of cells from patients affected by adult T-cell leukaemia, the haematological malignancy aetiologically associated with human T-lymphotropic virus type I (HTLV-I). In the present study, human neonatal lymphocytes were exposed to HTLV-I in vitro in the presence of IL-4. The results showed that: (i) cultures exposed to HTLV-I in the presence of either IL-4 or IL-2 bound IL-4; (ii) IL-4 did not substitute for IL-2 as a growth factor in cell lines previously infected and maintained in IL-2; (iii) cultures exposed to HTLV-I and maintained in IL-4 or IL-2 became infected; and (iv) IL-4 sustained the growth of HTLV-I-infected cultures for a maximum of 14 weeks. Moreover, HTLV-I-infected cultures grown in IL-4 showed upregulation of the IL-4 message and lower expression of HLA-DR and CD25 when compared with counterpart cultures maintained in IL-2. These results suggest that continuous growth of T-lymphocytes induced in vitro by HTLV-I infection, at least temporarily, requires signals specifically provided by IL-2 and not by IL-4.

Antiretroviral effect of combined zidovudine and reduced glutathione therapy in murine AIDS

A combination of antiretroviral drugs acting at different points in the virus replication cycle was evaluated in a murine retrovirus-induced immunodeficiency model of AIDS (MAIDS). Intramuscular administration of high doses of reduced glutathione (GSH, 100 mg/mouse/day) and AZT (0.25 mg/ml in drinking water) was found to reduce lymphoadenopathy (92%), splenomegaly (80%), and hypergammaglobulinemia (90%) significantly more than AZT alone. Combined treatment resulted in a reduction in proviral DNA content of 69, 66, and 60%, respectively, in lymph nodes, spleen, and bone marrow. Furthermore, the stimulation index of B cells was also significantly higher in animals receiving GSH and AZT whereas additional responses were not observed in the T cell stimulation index and blood lymphocyte phenotype analyses. In conclusion, the administration of high doses of GSH and AZT, a new combination of antiviral drugs, seems to provide additional advantages compared to single-agent therapy.

Intracellular GSH content and HIV replication in human macrophages

In vitro HIV-1 infection induced a significant decrease in intracellular reduced glutathione (GSH) in human macrophages. Such a decrease was observed at the time of infection corresponding to maximum release of virus from infected cells and was not related to cell cytotoxicity. GSH los was not related to its oxidation or leakage through the cell membrane. Inhibition of intracellular GSH synthesis by buthionine sulfoximine (BSO) did not further decrease GSH levels with respect to the decrease caused by HIV alone. However, treatment of macrophages with BSO significantly increased the HIV yield in the supernatant. Exogenous GSH strongly suppressed the production of p24 gag protein as well as the virus infectivity. Previous observations with other RNA and DNA viruses consistently showed that GSH antiviral effect occurred at late stages of virus replication and was related to the selective decrease of specific glycoproteins, such as gp120, which are particularly rich in disulfide bonds.

Combination therapy with BRMs in cancer and infectious diseases

In recent years many studies have stressed the importance of using biological response modifiers (BRMs) in the treatment of different conditions of immune-impairment correlated with ageing, cancer and infectious diseases. In particular, the use of different BRMs in conjunction with conventional therapies has been extensively explored. Our studies have demonstrated that treatment with Thymosin alpha-1 and low doses of IFN or IL-2 exert powerful biological effects both in vitro and in vivo. They are highly effective in restoring cytotoxic activities in immunosuppression induced by tumors and/or cytostatic drugs. In addition, when combined with specific chemotherapy, they are able to induce a dramatic inhibition of tumor growth in both experimental models and in humans. Immunotherapeutic treatment also has an application in controlling infectious diseases, especially those occurring in the immuno-compromised host. The advantage of using the combined immunotherapy treatment with antiviral drugs has been recently demonstrated by our group both in a murine experimental influenza model and in patients infected with HBV, HCV and HIV.

Antifungal and immunoadjuvant properties of fluconazole in mice immunosuppressed with morphine

We investigated the efficacy of fluconazole on experimental disseminated candidiasis in mice immunocompromised by chronic morphine treatment. CD1 mice were severely immunosuppressed by repeated morphine administrations, i.e., subcutaneous (s.c.) injections of 75 mg/kg/day, 3 days before and 5 days after a systemic Candida albicans infection induced by intravenous administration of 1 x 10(6) fungal cells/mouse. Fluconazole (2.5 mg/kg, s.c., at 6, 24 and 48 h postinfection) was very effective in prolonging survival time of morphine-treated mice. Fluconazole treatment also promotes a recovery of killing activity of polymorphonuclear leukocyte cells suppressed by morphine administrations.

Red blood cells mediated delivery of 9-(2-phosphonylmethoxyethyl)adenine to primary macrophages: efficiency metabolism and activity against human immunodeficiency virus or herpes simplex virus

Red blood cells (RBC) may act as selective carriers of drugs to macrophages, an important reservoir of viruses such as human immunodeficiency virus (HIV) and herpes simplex virus type 1 (HSV-1). We therefore assessed the incorporation of 9-(2-phosphonylmethoxyethyl)adenine (PMEA), a potent inhibitor of HIV and HSV-1) into RBC, its delivery to macrophages and its activity against HIV or HSV-1. Loading of PMEA in artificially aged opsonized RBC affords significant levels of intracellular PMEA. RBC metabolize PMEA to its active congener PMEA-diphosphate, although with low efficiency. Exposure of macrophages to RBC-encapsulated PMEA inhibits the replication of both HIV and HSV-1 (about 90% inhibition at the highest RBC:macrophages ratios) even if RBC were removed before virus challenge. By contrast, the antiviral activity of free PMEA removed before virus challenge was irrelevant at concentrations up to 150-fold higher than the 50% effective concentration (EC50). Finally, the antiviral effect of RBC-encapsulated PMEA correlates with PMEA levels in macrophages about 500-fold higher than those achieved by free PMEA (at concentrations 10-fold higher than the EC50). The efficacy of RBC-mediated delivery to macrophages of PMEA (and perhaps of compounds with shorter intracellular half-lives) warrants further studies in infectious diseases involving phagocytizing cells as main targets of the pathogen.

Loss of GSH, oxidative stress, and decrease of intracellular pH as sequential steps in viral infection

Madin-Darby canine kidney cells infected with Sendai virus rapidly lose GSH without increase in the oxidized products. The reduced tripeptide was quantitatively recovered in the culture medium of the cells. Since the GSH loss in infected cells was not blocked by methionine, a known inhibitor of hepatocyte GSH transport, a nonspecific leakage through the plasma membrane is proposed. UV-irradiated Sendai virus gave the same results, confirming that the major loss of GSH was due to membrane perturbation upon virus fusion. Consequent to the loss of the tripeptide, an intracellular pH decrease occurred, which was due to a reversible impairment of the Na+/H+ antiporter, the main system responsible for maintaining unaltered pHi in those cells. At the end of the infection period, a rise in both pHi value and GSH content was observed, with a complete recovery in the activity of the antiporter. However, a secondary set up of oxidative stress was observed after 24 h from infection, which is the time necessary for virus budding from cells. In this case, the GSH decrease was partly due to preferential incorporation of the cysteine residue in the viral proteins and partly engaged in mixed disulfides with intracellular proteins. In conclusion, under our conditions of viral infection, oxidative stress is imposed by GSH depletion, occurring in two steps and following direct virus challenge of the cell membrane without the intervention of reactive oxygen species. These results provide a rationale for the reported, and often contradictory, mutual effects of GSH and viral infection.

Cocaine increases Sendai virus replication in cultured epithelial cells: critical role of the intracellular redox status

Cocaine was found to increase parainfluenza-1 Sendai virus (SV) replication in Madin Darby canine kidney (MDCK) cells. Its effect was maximal when it was added before SV infection, while practically no effect was observed when cocaine was added at the time of or after infection. Enhanced SV replication was associated with increased viral protein expression. Cocaine also greatly reduced the intracellular level of glutathione (GSH), namely the most abundant cell thiol with antioxidant functions, recently proposed as an important factor influencing viral infection. Support for this view was provided in the present study by the reversal of cocaine-induced enhancement of SV replication when the intracellular content of GSH was restored by addition of exogenous GSH.